Conceived in 1937, the machine was built by Iowa State College mathematics and physics professor John Vincent Atanasoff with the help of graduate student Clifford Berry.

However, its intermediate result storage mechanism, a paper card writer/reader, was not perfected, and when John Vincent Atanasoff left Iowa State College for World War II assignments, work on the machine was discontinued.

[10] According to Atanasoff's account, several key principles of the Atanasoff–Berry computer were conceived in a sudden insight after a long nighttime drive to Rock Island, Illinois, during the winter of 1937–38.

A grant application to build a proof of concept prototype was submitted in March 1939 to the Agronomy department, which was also interested in speeding up computation for economic and research analysis.

Each gate consisted of one inverting vacuum-tube amplifier, preceded by a resistor divider input network that defined the logical function.

The control logic functions, which only needed to operate once per drum rotation and therefore did not require electronic speed, were electromechanical, implemented with relays.

Selection of the operation to be performed, reading, writing, converting to or from binary to decimal, or reducing a set of equations was made by front-panel switches and, in some cases, jumpers.

Intermediate results were binary, written onto paper sheets by electrostatically modifying the resistance at 1500 locations to represent 30 of the 50-bit numbers (one equation).

The reliability of the system was limited to about 1 error in 100,000 calculations by these units, primarily attributed to lack of control of the sheets' material characteristics.

George W. Snedecor, the head of Iowa State's Statistics Department, was very likely the first user of an electronic digital computer to solve real-world mathematics problems.

[15] On June 26, 1947, J. Presper Eckert and John Mauchly were the first to file for patent on a digital computing device (ENIAC), much to the surprise of Atanasoff.

Campbell-Kelly and Aspray conclude:[18] The extent to which Mauchly drew on Atanasoff's ideas remains unknown, and the evidence is massive and conflicting.

Judge Larson explicitly stated: Eckert and Mauchly did not themselves first invent the automatic electronic digital computer, but instead derived that subject matter from one Dr. John Vincent Atanasoff.Herman Goldstine, one of the original developers of ENIAC wrote:[19] Atanasoff contemplated storing the coefficients of an equation in capacitors located on the periphery of a cylinder.

During the period of Atanasoff's work on his linear equation solver, Mauchly was at Ursinus College, a small school in the environs of Philadelphia.

The discussion greatly influenced Mauchly and through him the entire history of electronic computers.The original ABC was eventually dismantled in 1948,[20] when the university converted the basement to classrooms, and all of its pieces except for one memory drum were discarded.

In 1997, a team of researchers led by Delwyn Bluhm and John Gustafson from Ames Laboratory (located on the Iowa State University campus) finished building a working replica of the Atanasoff–Berry computer at a cost of $350,000 (equivalent to $664,000 in 2023).